EP0541810B1

EP0541810B1 - Disaster relief robot and its operation controller

Info

Publication number: EP0541810B1
Application number: EP91914221A
Authority: EP
Inventors: Koji Komatsu Research Department Ogaki; Tomowo Komatsu Research Department Matsuda; Kimihiko Komatsu Research Department Takagi; Takuya Komatsu Research Department Sakamoto
Original assignee: Komatsu Ltd
Current assignee: Komatsu Ltd
Priority date: 1990-08-08
Filing date: 1991-08-08
Publication date: 1996-10-23
Anticipated expiration: 2011-08-08
Also published as: US5337846A; EP0541810A4; ATE144474T1; DE69122872D1; DE69122872T2; WO1992002398A1; EP0541810A1; CA2088356A1

Abstract

A disaster relief robot and its operation controller. When relief goods, medicines, foods, etc., are transported outdoors to the site of disasters such as earthquakes, heavy rainfalls, landslides, etc., at the time of a wide area disaster, the present invention can prevent accidents such as the drop from cliffs, etc., and can secure also safety of an operator. To this end, track frames (16) of a crawler are fitted pivotally to the right and left sides at both of the front and rear portions of a robot body (10). The distance (L) between the pivots of front and rear crawlers (12F, 12R) is such that the maximum loci (CF, CR) of the front and rear crawlers may not meet, and the centroid (G) of the robot body exists at the intermediate position of the distance (L). The present invention proposes also various kinds of operation controllers. <IMAGE>

Description

TECHNICAL FIELD

The present invention relates to a disaster relief robot which can prevent a downfall over a precipice or the like while can ensure a safety of an operator when field transportation of relief supplies such as relief apparatus and materials, medicines or food stuffs in the case of a wide-area disaster caused by an earthquake, a heavy rain, a landslide or the like, and also relates to an operation controller for the robot.

BACKGROUND

Heretofore, there has been provided a remote-controlled travelling robot which incorporates four travelling crawlers and which is used for disposal of dangerous substance in a nuclear power facility or on a flat land (refer to, for example, Japanese Patent Publication No. 63-270 ). As shown in Fig. 18, this robot is arranged such that crawlers 2, independent from each other, are provided at four corners of a robot body 1, that is, they are attached to the robot body 1 through the intermediary of pivot shafts 2a, respectively, so that they can be turned, independent from each other. Accordingly, in addition to that the crawlers are laid horizontally for normal travel, they are made to stand upright for smooth movement in a narrow space and they are inclined for overriding a bump.
However, in the case of outdoor using the conventional robot on an off-road place or a place around a stricken area in a wide-area disaster, the robot is remote-controlled in its alert posture such that the rear crawlers 2R are inclined in a cave-in area to direct a stereo camera 3 mounted on the robot body 1 downward forward, as shown in Fig. 19(a). Although the robot can he operated with a certain caution in indoor use since there is no obstacle disturbing the field of view of the camera 3, but, in the case of outdoor use around the stricken area, the field of view is possibly disturbed by obstacles such as weeds so that the robot continue sometimes to advance even though the front crawlers 2F come off from the ground as shown in Fig. 19(b). Should it continue to advance, the front crawlers 2F would come off in its entirety so that the gravitational center of the robot body is shifted forward. In such a case, although the operator instruct, in a hurry, the robot to go back (as shown in Fig. 19(c)), the robot falls into the cave-in since the gravitational center of the robot body is shifted toward the cave-in (as shown in Fig. 19(d)). Alternatively, as shown in Fig. 19(e), even though it is initially found that the robot body 1 is inclined forward, whether it is caused by a concavity or convexity, or a cave-in cannot be at first discriminated well. Accordingly, the advance of the robot is continued with monitoring. Even through an instruction for go-back is issued due to the fact that an increase in inclination is found, the robot slips (as shown in Fig. 19(f)) and then falls into the cave-in since the gravitational center of the robot body is shifted toward the front crawlers 2F (as shown in Fig. 19(d)). In particular, not so large gripping force cannot be obtained if it travels on a muddy, sandy or weedy place, and accordingly, the robot tends to slip.
Further, in the case of climbing a bump, the robot normally travels until the front crawlers 2F come into contact with the bump as shown in Fig. 20(a). Then, the robot further advances while the front crawlers 2F is turned up and elevated (as shown in Fig. 20(b), and thereafter, the front and rear crawlers 2F, 2R are turned down in order to raise the robot body 1 (as shown in Fig. 20(c)) so that the robot advances to make the rear crawlers 2R into close contact with the surface of the bump as possible as it can (refer to Fig. 20(d)). However, the gravitational center of the robot body 1 would be shifted rearward so that the robot falls over the bump (refer to Fig. 20(f)) since the gravitational center of the robot body is not always stable on the bump, if the rear crawlers 2R are forced to climb the bump in such a condition that the rear crawlers 2R make into contact with an inclined surface of the bump (as shown in Fig. 20(e)) and the rear crawlers 2R are turned up and elevated.
The conventional travelling robot is likely to have a risk of a downfall as mentioned above in a natural environment in which a cave-in or a bump is there as in a stricken area in a wide-area disaster, and accordingly, their actual activities have to be greatly limited. Further, upon occurrence of accident of a downfall, a power transmission system, a structural member or the like is damaged, and accordingly, there is raised a problem of impossible use of the travelling robot.
Such a remote-control of the robot is carried out by the operator who manipulates four knobs laid on the flat board of a control, for respectively controlling the postures of the crawlers. The rotating angles of the respective knobs exhibit the turning angles of the four crawlers, respectively.
However, should the robot having a three-dimensional shape be remote-controlled by means of the knobs laid in a planar configuration, the operator should carry out the posture control for every crawler while imaging its posture in motion. In particular, such an imaginal control cannot at once cope with an instant delay in operation and an error in operation in the case of operation of the robot in an off-road place such as a stricken area. Further, a deviation occurs between the actual turn angle of each of the crawlers and the rotating angle of the associated knob. Moreover, the operator cannot finely and timely remote-control the robot since the such a data that each of the rollers comes to a stop before fulfilling a turn-angle instruction due to a turning resistance is not fed back to the knob. That is, the operator cannot remote-control the robot with directly feeling in his body the posture of each of the crawlers, and accordingly, there has been raised such a problem that robot falls in a downfall or a sidewise turn-over during its operation.
Further, in the case of travel on such an off-road place, the operator has to remote-control the robot while monitoring an inclinometer or the like always with paying the closest attention thereto in order to prevent the robot from falling down over a precipice. That is, whether the robot falls down or not is dependent upon the operator's abilities of monitor and skill in manipulation, and accordingly, the operator has to be greatly strained. Further, a care should be taken for preventing the operator himself from falling down, in addition to payment of care for safety operation of the robot. Accordingly, if the operator has to remote control the robot over a long distance in an stricken area in a wide area disaster while he accompanies with the robot, he exhausts greatly, and accordingly, there is a fear that he himself falls into an accident such as a downfall over a precipice, and further, his abilities of monitor and skill in manipulation deteriorate, resulting in a problem of erroneously causing the robot to fall down.
The present invention is devised in view of the above-mentioned problems, and accordingly, one object of the present invention is to provide a disaster relief robot which can travels on an off-road place stricken by a wide area disaster with no hindrance in running over a cave-in place or a bump, and in which a drive system is not damaged even by a shock in a downfall or the like, and further to provide a maneuver control device for a disaster relief robot, with which the robot cannot be remote-controlled with a high responsiveness while the posture of each of the crawlers is grasped with direct feeling, and further, which can surely prevent occurrence of a downfall without requiring the operator's ability of monitor or the like so that a safety can be ensured without exerting great stress to the operator.
A disaster relief robot with the features of the preamble of claim 1 is known from JP-A-63 203 483. Do to the small distance between the front and the rear crawlers it is however not possible to obtain the variety of operation positions which will be explained later on in respect to figures 6 to 8 of the present invention.
Futher hacked vehicles are known from EP-A-0 466 574 and EP-A-0 427 999.

DISCLOSURE OF THE INVENTION

A disaster relief robot according to the present invention, comprising a pair of left and right crawlers with rubber tracks provided on each of the front and rear sides of a robot body, the crawlers each have sprockets which are driven and controlled, independent from each other, so as to run the robot, wherein a track frame of each crawler is turnably attached to the robot body through the intermediary of a pivot shaft, which is arranged transverse to the track frame and parallel to the rubber track surface and being located on one end side of said track frame, characterized in that the inter shaft distance between the pivot shafts of the front and rear crawlers are set so that maximum turning loci of them do not interfere with each other, and the gravitational center of the robot body is set at a position intermediate of the distance between the pivot shafts in the front and rear crawlers.
Further, a torque limiter is arranged in a turning power transmission system in each track frame of the crawler so that the torque transmission can be cut off when a turn reaction force transmitted from the track frame side exceeds a predetermined value. Further, a sensor for detecting a turn angle may be attached to the turning power transmission system between the torque limiter and the track frame.
With this arrangement, a maximum extended condition in which the front ends of the turned front and rear crawlers are positioned outside of the robot body and a minimum condition in which the front ends are in close proximity to each other can be taken. Accordingly, upon running over a cave-in or a bump, only the front crawlers are extended forward, and accordingly, it is reversed so as to be moved back when the front crawlers come off from an inclined surface of a cave-in, thereby it is possible to prevent the robot from falling. Further, in the case of climbing up a bump, the rear crawlers are inclined downward so as to raise and move the robot body after the front crawlers are moved onto the top part of the bump in order to shift the gravitational center of the robot body toward the other side of the top part of the bump, and then the rear crawlers are further turned so as to return the robot body to its original posture, thereby it is possible to climb the bump. Further, with the provision of the torque limiter, a bumping force exerted to the crawlers to be turned does not directly affect the power source, and accordingly, a motor and a power transmission having a high gear ratio can be protected even though an external force in a turning direction is forcibly exerted by a bumping force upon a downfall. Further, the provision of the angle sensor for detecting a turn angle, an actual turn angle can be measured even through a deviation occurs in correspondence between the drive side turn angle and the track frame side turn angle, and accordingly, the operation control can be continued even though the turn angle of the track frame unexpectedly varies due to a downfall or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic view illustrating a drive mechanism of a disaster relief robot according to the present invention;
Fig. 2 is a side view illustrating the robot shown in Fig. 1;
Fig. 3 is a plan view illustrating the robot; Fig.4 is a front view illustrating the robot, Fig. 5 is a block diagram illustrating a maneuver control system of the robot; Fig. 6 is a view for explaining the operation of the robot at a drop-off; Fig. 7 is a view for explaining a bank overriding operation of the robot; Fig. 8 is a view for explaining a typical posture the robot can take;
Fig. 9 is a schematic perspective view illustrating a controller with which a first embodiment of an operation controller according to the present invention is explained;
Fig. 10 is a schematic external view illustrating a robot body; Fig. 11 is a view illustrating an inter connection among the controller, a control device and the robot body, relating the operation controller shown in Fig. 9; Fig. 12 is a block diagram illustrating a maneuver control system based upon Fig. 11; Fig. 13 is a flow chart for explaining an operation of the operation controller carried out by a microcomputer; Fig. 14 is a schematic perspective view illustrating a controller with which a second embodiment of the operation controller according to the present invention is explained; Fig. 15 is a block diagram illustrating a remote control system based upon Fig. 14;
Fig. 16 is a flow-chart for explaining a third embodiment of the operation controller according to the present invention; Fig. 17 is a view for explaining an operation of the robot coping with the process shown in Fig. 16;
Fig. 18 is a perspective view illustrating a conventional travelling robot; Fig. 19 is a view for explaining the operation of the conventional travelling robot in a cave-in place; and Fig. 20 is a view illustrating a bank overriding operation of the conventional travelling robot.

BEST MODE FOR CARRYING OUT THE INVENTION

Detailed explanation will be hereinbelow made of a disaster relief robot and specific embodiments of an operation controller therefor, according to the present invention, with reference to the drawings.
Fig. 1 is a schematic view illustrating a drive mechanism of a disaster relief robot according to the present invention, and Figs. 2 to 4 are external views illustrating the robot. This robot incorporates crawlers 12F(R) which are turned by drive sources independent from each other, respectively, at four corners of a robot body 10. A track frame 16 for each of the crawler 12F(R) incorporates a pivot shaft 14, and accordingly, the track frame 16 is attached to the body so that it can be turned by an angle of 360 deg. about the pivot shaft 14. In this arrangement, the front and rear crawlers 12F, 12R on one side of the robot body 10 are attached to the robot body 10 so that their pivot shafts 14 are spaced from each other in order to prevent their maximum turning loci CF, CR from overlapping with each other. That is, the inter pivot shaft distance L between the front and rear crawlers 12F, 12R is set to be greater than the sum of the radii of these maximum turning loci CF, CR. Further, setting is made such that the gravitational center G of the robot body 10 passes through a position intermediate between these maximum turning loci CF, CR, and that the ground contact position of the front and rear crawlers 12F, 12R are always outside of the gravitational center G of the body. Accordingly, the front and rear crawlers 12F, 12R are located at positions near to the front and rear ends of the robot body 10. In the turning operation of these crawlers, a maximum extended condition in which the turning front ends of the front and rear crawlers 12F, 12R are extended respectively in the front and rear of the robot body 10, and a minimum retracted condition in which the turning front ends are directed toward the gravitational center of the robot body can be taken.
Explanation will be made of a drive mechanism for the crawler 12F(R) attached to the robot body 10 as mentioned above. The crawler 12F(R) is composed of the track frame 16, a drive sprocket 20 located on one end side of the track frame 16, an idler 21 located on the other end side thereof, rotary wheels 22 disposed between the sprocket and the idler, and a rubber track 18 wound around thereof. The travelling rotary shaft 24 of the sprocket 20 pierces into the robot body 10 and is rotated by a travelling motor 26 through the intermediary of a reduction gear 28 and a chain 30. Further, the rubber track 18 is driven so as to be rotated around the outer periphery of the track frame 16, and accordingly, the robot can travel.
Further, the pivot shaft 14 is a cylindrical shaft in which a travelling rotary shaft 24 is enclosed, and is made to pierce into the robot body 10 from each end part of one side surface of the robot body 10 through the intermediary of a bearing. A gear 32 which is rotatably fitted on the outer peripheral surface of the pivot shaft 14, is integrally incorporated with the latter by means of a torque limiter 34. Meanwhile, a turning motor 36 and a reduction gear 38 for applying a drive torque to the gear 32 are provided in the robot body 10, and a drive gear 40 fitted on the output shaft of the reduction gear is coupled with the gear 32 through the intermediary of an intermediate gear 42. Accordingly, the drive torque of the turning motor 36 is transmitted to the pivot shaft 14 by way of the reduction gear 38, the drive gear 40, the intermediate gear 42, the gear 32 and the torque limiter 34 so as to turn the track frame 16 of the crawler 12F(R). The above-mentioned torque limiter 34 is adapted to cut off the power transmission path when a forcible turning force is applied to the crawler 12F(R) due to a downfall or the like, and accordingly, the engagement between the pivot shaft 14 and the torque limiter 34 fitted on the pivot shaft 14 is released.
A rotary encoder 44 is attached to the pivot shaft 14 so as to detect a rotational position of the pivot shaft 14 or a turning position of the track frame 16. In particular, this encoder is provided on a turn transmission path extending from the torque limiter 34 to the track frame 16.
The above-mentioned drive mechanism is independently provided in each of the crawlers 12F(R), and is adapted to solely carry out traveling drive and turning operation. Fig. 5 is a block diagram illustrating a maneuver control system for the robot. This robot is remote-controlled by a maneuver signal from a remote control transmitter 46. Thus, a remote control receiver 48 and a control device 50 are disposed in the robot body 10. This control device 50 receives the maneuver signal and delivers a fuel control signal to an engine control device 52 for controlling an engine 54. The engine 54 drives a power generator 55 serving as a power source for the travelling motors 26 and the turning motors 36. Further, the control device 50 delivers a control signal to motor drive power source devices 56, 58 for regulating the rotating powers to the motors 26, 36 while it receives measurement signals from speed control encoders 60, 62 so as to perform feed-back control in order to set a travelling speed and a turning angle in accordance with the above-mentioned maneuver signal. Further the control device 50 directly receives an output signal from the encoder 44 for detecting a rotating angle of the pivot shaft 14, and also receives a measurement signal from an inclinometer 64 for detecting an inclination of the robot body 10.
Next explanation will be made of operation of the thus constituted disaster relief robot. In the case of such an anticipation that the robot possibly falls down due to a precipice or a cave-in in a disaster area, an abnormal inclination of the robot body 10 on advance is detected with the use of an output signal from an inclinometer 64 mounted on the robot without using a visual detection so as to issue an abnormal alarm so as to call the attention of the operator, and to recover its posture in order to prevent the entire robot from falling down even though the front crawlers 12F falls down into the cave-in.
That is, as shown in Fig. 6(a), in an area in which the presence of a downfall is anticipated, the robot travels with such a survey posture that the front crawlers 12F are turned, and accordingly, their ends are positioned in front of the robot body 10 while the front ends of the rear crawlers 12R are positioned on the gravitational center side of the robot body 10. When the front crawlers 12F comes off during the travel, the robot body 10 is inclined forwardly downward (as shown in Fig. 6(b)). At this time, it cannot be clearly found whether the inclination is caused by come-off at a cave-in or at a concavity and a convexity on the ground surface. Thus, the advance is continued. If it is caused by the come-off at a cave-in, the front crawlers 12F completely fall down into the cave-in, that is, the front section of the robot body 10 comes into contact with the ground surface just before the cave-in (Fig. 6(c)). In this condition, the front crawlers 12F races or exhibits an abnormally light load while the inclinometer 64 indicates an abnormally inclined condition, and accordingly, an automatic determination can be made. The operator who hears the alarm issued at that time, reverses the travelling motors 26 so as to rapidly brake the crawlers in order to stop the robot body 10. Then, the front crawlers 12F are turned up so as to return the robot into its reference posture in which the turning front ends of the front and rear crawlers 12F, 12R are in proximity to each other (as shown in Fig. 6(d)). Since the turning loci of the front and rear crawlers 12F, 12R do not overlap with each other, this turning operation can be readily made. In this case, if the position just before the cave-in is inclined forward, the substantial part of the weight of the body is applied to the front crawlers 12F, and accordingly, if the front half parts of the crawlers 12F have entered into the cave-in, no grip force sufficient for supporting the load can be exhibited. Accordingly, the front crawlers 12F are further turned so as to raise the front section of the robot body 10 in order to rearward shift the gravitational center of the robot body, and therefore, the rear crawlers 12R are applied with a load. thereby it is possible to obtain a stable gripping force (Fig. 6(e)). After the robot goes back to a sufficiently safe position (Fig. 6(f)), the robot is returned again into the survey posture, and then, the robot goes into another course.
Next explanation will be made of a bank overriding operation of the disaster relief robot with which the robot travels over a bump, with reference to Fig. 7.
At first, as shown in Fig. 7(a), when the robot in the survey posture abuts against a bump, the front crawlers 12F are turned up and so as to hook their front ends onto the top part of the bump (as shown in Fig. 7(b)). Then, the front and rear crawlers 12F, 12R are turned down so as to raise the robot body 10 (as shown in Fig. 7(c)), and the turning is stopped when the bottom section of the robot body 10 becomes higher than the top part of the bump, and then it is advanced as it is (as shown in Fig. 7(d)). After the rear crawlers 12R reach an inclined surface of the bump, their rear ends of the rear crawlers 12R are turned up, and accordingly, the crawlers 12R are advanced while the front end sides thereof are made into close contact with the inclined surface (as shown in fig. 7(e)). In this stage, since the gravitational center of the robot body has sufficiently come onto the bump so as to be stable thereon, the rear section of the robot body 10 supports the weight of the body in such a condition that the rear section of the robot body 10 makes contact with the ground surface, thereby it is possible to prevent the robot body 10 from slipping down rearward (as shown in Fig. 7(f)). Accordingly, the upward turning is continued to recover the original posture (as shown in Fig. 7(g)), and accordingly, it can be advanced again (as shown in Fig. 7(h).
Further, if a downfall accident occurs, a large impact force is applied to the crawlers 12 so as to tend to forcibly turn the same. This external turning force is to forcibly rotate the pivot shaft 14 so as to produce an excessive torque. However, since the torque limiter 34 is disposed intermediate of the power transmission system, no impact force is transmitted to the power source. Accordingly, it is possible to surely prevent the turning motors 36 and the transmission mechanism having a high gear ratio from being damaged. Further, since the encoder 44 for detecting a turning angle is fitted on the pivot shaft 14, a turning angle can be detected even though the transmission system between the crawlers 12 and the power source is cut off. Accordingly, even though a deviation is produced in the correspondence between the rotating angle of the turning motor 36 and the associated crawler 12, the control system of the robot can precisely measure the updated turning angle of the crawler 12. Accordingly, even though the crawler 12 is forcibly turned up to an unexpected angle since it encounters an unexpected downfall accident, the operation control can be at once continued just after that.
Since the thus constituted disaster relief robot has a large space between the pivot shafts 14 of the front and rear crawlers 12F, 12R in addition to the above-mentioned function, there can be taken a storage posture in which the length and height of the robot are minimum as shown in Fig. 8(a), the reference posture (as shown in Fig. 8(b), and a bridging posture (as shown in Fig. 8(c)), a steep slope climbing posture (as shown in Fig. 8(d)) and the like. It is noted that a winch may be attached to the front or rear section of the robot body 10 so that one end part of a wire rope is wound on a tree or a rock while the other end part thereof is wound up (ascent) or paid off (descent) by the winch in order to assist the ascent and the descent or to prevent the robot from dropping, thereby it is possible to ascend or descend a steep slope with a more safe manner.
With the disaster relief robot according to the present invention, the capability of overriding a bump is greatly enhanced, which is several times as large as that of the conventional one, and a downfall accident can be avoided even though a cave-in is encountered, thereby it is possible to safely transport relief supplies in an outdoor disaster field. Further it is possible to prevent damage to the drive mechanism or a damage thereto can be compensated for by a simple repair even though a downfall accident occurs, and accordingly, it is possible to safely and surely transport a large number of relief supplies in a short time.
Next, explanation will be made in detail of a first embodiment of the operation controller according to the present invention with reference to Figs. 9 to 13. Referring to Fig. 9, a controller 71 for remote control incorporates four rotating angle detectors 72a, 72b, 72c, 72d, and knobs 73a, 73b, 73c, 73d for controlling the postures of the crawlers are fitted onto the shafts of the detectors, respectively. These four rotating angle detectors 72a, 72b, 72c, 72d are adapted to set desired values of the turning angles of four crawlers 12a, 12b, 12c, 12d of the robot body 10 when the operator manually remote-controls the turning angles of the four crawlers. The four knobs have a flattened shape, each having, at their one longitudinal end, marks 74a, 74b, 74c, 74d, and are arranged on opposite sides of the controller 71, at two positions on each side. The operator can grasp, by intuition, the respective turning angles of the four crawlers 12a, 12b, 12c, 12d whenever he observes the four knobs 73a, 73b, 73c, 73d on the controller 71, and accordingly, it is possible to enhance the remote controllability.
Explanation will be made of operation of the first embodiment of the operation controller according to the present invention. As shown in Fig. 10, the four crawlers 12a, 12b, 12c, 12d are turned by 360 deg. by means of turning motors 36a, 36b, 36, 36d. in order to detect actual turning angles thereof, turning angle detectors 44a, 44b, 44c, 44d are attached. Fig. 11 shows the relationship among the controller 71, a control device 82 and the robot body 10. The rotating angle detectors 72a, 72b, 72c, 72d deliver signals 75a, 75b, 75c, 75d indicating desired turning angles of the crawlers in accordance with rotating angles of the knobs on the controller 71, as input signals to the control device 82 which delivers turning drive voltage signals 80a, 80b, 80c, 80d to the turning motors 36a, 36b, 36c, 36d. The turning angle detectors 44a, 44b, 44c, 44d detect turning angles of the turning motors and deliver turning angle signals 81a, 81b, 81c, 81d as input signals to the controller 82.
One of the four maneuver control system will be explained with reference to Fig. 12 which is a block diagram. Referring to this figure, a difference between the desired crawler turning angle signal 75 delivered from the rotating angle detector 72 and the turning angle signal 81 fed back from the turning angle detector 44 is inputted to a control circuit 88 which is an amplifier for carrying out, for example, PID control, and which incorporates a power amplifier for generating a voltage as an output sufficient to drive the turning motor 36.
Fig. 13 is a flow-chart for explaining the operation of the operation controller with the use of a microcomputer. First, at step 101, the desired turning angle signal 75 is inputted from the rotating angle detector 72. If the rotating angle detector 72 is a multiple rotation type potentiometer, the output signal thereof is a voltage which is therefore converted, by an A/D converter, into the desired turning angle signal 75 which is then inputted. If the rotating angle detector 72 is an increment type two phase pulse encoder, the output signal thereof is a serial pulse signal having a logic output voltage (or current), and accordingly the desired turning angle signal 75 is inputted with the use of a counter. Further, if the rotating angle detector 72 is an absolute type pulse encoder, the output signal thereof is a parallel pulse signal having a logic output voltage (or current), and accordingly, the desired turning angle signal 75 is inputted with use of a parallel peripheral input. Any one of combinations having a function which can detect the above-mentioned rotating angle can be used as the above-mentioned combination. Next, at step 102, an actual turning angle of the crawler is inputted as a feed-back signal 81 from the turning angle detector 44. A combination similar to that of the above-mentioned rotating angle detector 72 can be used for the turning angle detector 44 and its input circuit. Then, at step 103, the desired turning angle signal 75 and the feed-back signal 81 are compared with each other so as to compute an angular difference therebetween. This angular difference is positive if it is within 180 deg. as measured clockwise, but is negative if it is less than 180 deg. as measured counterclockwise. At step 104 which is in the case of a dead zone provided in the maneuver control system. If the absolute value of the angular difference is less than a predetermined numerical value set as the dead zone, the procedure is advanced to step 105 so that no signal is delivered to the turning motor 36. On the contrary, if it is larger, the procedure is advanced to step 106 where whether the angular difference is a positive value or a negative value is examined. If the angular difference is positive, the procedure is advanced to step 107 where a positive voltage is fed to the turning motor 36 which is therefore rotated normally. On the contrary, if the angular difference is negative, the procedure is advanced to step 108 where a negative voltage is fed to the turning motor 36 which is therefore reversed. At step 109, it is determined whether the procedure is continued in the case of receiving an abnormal signal or the procedure is completed in the case of receiving a completion instruction. In the case of the continuation, the procedure is returned to step 101 so as to repeat the above-mentioned operation, but in the case of the completion, this program is completed.
Next, explanation will be made of a second embodiment in which a bilateral control means is applied to the above-mentioned operation controller, with reference to Figs. 14 and 15. It is noted that the arrangement of the robot body is similar to that shown in Fig. 10, and that only one of the four control systems will be explained for the sake of brevity.
As shown in Fig 14, four knobs 93 for controlling the postures of the crawlers are attached to opposite inclined surfaces of a controller 91 in order to rotate the shafts of rotating angle detectors 92. These rotating angle detectors 92 are driven by small motors 96 through the intermediary of gears 95, 97. A mark 94 is provided at one longitudinal end of each of the knobs 93. Thus, referring to Fig. 15 which is a block diagram, this embodiment will be explained. An output signal 99 delivered from the rotating angle detector 92 incorporated in the controller 91 is compared with a turning angle signal 81 from the turning angle detector 44 incorporated in the robot body 10, by means of the control device 89. The thus obtained difference signal is delivered to the control circuit 88 for the turning motor 36 in the robot body 10, and to a control circuit 98 for the small motor 96 in the controller 91. The former control circuit 88 treats the output signal 99 from the rotating angle detector 92 as a desired turning angle signal, and a turning angle signal 81 from the turning angle detector 44 as a feed-back signal. Thus, the turning motor 36 attached to the robot body 10, generates a force which causes the crawler to turn up to an angle set by the rotating angle detector 92 in the controller 91. On the contrary, the latter control circuit 98 treats the turning angle signal 81 from the turning angle detector 44 as a desired rotating angle signal at the rotating angle detector, and the output signal 99 from the rotating angle detector 92 as a feed-back signal. Accordingly, the greater the difference from the present value at the turning angle detector 44, the larger the force for returning the posture of the crawler to the present value is produced by the small motor 96 attached to the controller 91. In this second embodiment, the flow-chart for the operation using a microcomputer is similar to that shown in Fig. 13. That is, paying attention to the fact that the relationship between the desired value signal and the feed back signal in the case of the control circuit 98 is contrary to that in the case of the control circuit 88, it can be regarded as the same as the flow-chart in the case of the control circuit 88 shown in Fig. 13. That is, if the turning motor in the robot body 10 is in a light load condition so that the turning motor 36 is rotated as soon as the knob 93 on the controller is rotated, the force with which the small motor 96 in the controller 93 reversely rotates the knob 93 toward the present value of the angle of the crawler is decreased. On the contrary, if the turning motor is in a heavy load condition so that the turning motor 36 can be hardly rotated even though the knob 93 on the controller 91 is rotated, the force with which the small motor 96 in the controller 91 reversely rotates the knob 93 toward the present value of the angle of the crawler is increased. Therefore, the operator has to rotate the knob 93 with his strength. That is, with the application of the bilateral control means in the above-mentioned operation controller, the operator can not only directly feel the posture of the crawler of the robot body 10 from the rotating angle of the knob 93 on the controller, but also can feel in his body the load condition of the crawler in the form of the turning resistance as the knob 93 is rotated. It is noted that any bilateral system other than the bilateral system which is explained in reference to Fig. 15 and which is well known as a symmetric type in the society in the field or the like, such as that of a force feed-back type or an impedance type can be used to constitute the operation controller according to the present invention, instead of the symmetric type in the above-mentioned embodiment.
Thus, when the disaster relief robot slips at a precipice or on a slope, or when the robot stumbles over a stone or a wood piece so that its posture becomes unstable, the posture of the robot can be grasped with a high response, and accordingly, the operation of the robot can be surely and safely carried out.
Next, a third embodiment of the operation controller according to the present invention will be explained in detail, referring particularly to Figs. 16 and 17. Incidentally, the drive mechanism for turning and running the disaster relief robot is the same as that shown in Figs. 1 to 8.

(1) Survey Posture Process

If the operator feels that the disaster relief robot which travels in a cave-in zone including a precipice or the like has to prepare for preventing a downfall in the case of an accident, he turns on a "downfall preventing switch" which is incorporated in the remote-control transmitter 46 and which is not shown. At this time, the process shown in Fig. 16 is started. At first, the turning angles of the front and rear crawlers 12F, 12R of the robot body 10 are controlled by the power source device 58 for driving the turning motors, and accordingly, as shown in Fig. 17(a), the front crawlers 12F are set at a turning angle θ1 at which the front crawlers 12F are extended forward from the robot body 10 while the rear crawlers 12R are set at a turning angle θ2 at which the rear crawlers 12F are extended toward the gravitational center F of the robot body. It is noted that the turning angle θ2 is set to zero when the longitudinal direction of the front and rear crawlers 12F, 12R is parallel with the horizontal line HR and the front ends 12a, 12b thereof are directed to the gravitational center G of the body. The posture at this time will be hereinbelow denoted as "reference posture".
When the robot advances in the above-mentioned survey posture, the control device 50 samples deviations in speed control systems for the front crawlers 12F and outputs from the inclinometer 64 so as to pick up loads exerted to the front crawlers 12F and a longitudinal inclined angle of the robot.
Explanation will be hereinbelow made of the way of obtaining a load exerted to the front crawler 12F from a deviation in the speed control system for the front crawler 12F.
At the time of starting the process shown in Fig. 16, the gain of a control loop in the speed control system of the traveling motor 26 of the front crawler 12F is set to a remarkably low value. In this case, it can be considered in particular that the proportional gain or an integration gain of the control loop in the speed control system for the traveling motor 26 is adjusted to a lower value, or a current limitation or a torque limitation is applied to a servo-motor power source device 56 for the travelling motor 26 in order to prevent the traveling motor 26 from producing a torque exceeding a predetermined value. It is noted that the control loop gain of the travelling motor 26 for the rear crawler 12R is set to a value which is sufficient for reaching a desired speed given by the control device 50, irrespective of a load applied to the rear crawler 12R. With this arrangement, the travelling control can be made mainly by the drive force of the travelling motor 26 for the rear crawler 12R while the travelling motor 26 for the front crawler 12F only produce a torque compensating for a mechanical loss, for example, in the speed reduction gear 28. In other words, such a case that the travelling motor 26 for the front crawler 12F is rotated at a speed corresponding to the desired speed, is that the front crawler 12F mainly makes contact with the ground surface while the robot body 10 is propelled by the drive force of the travelling motors 26 of the rear crawlers 12R, and accordingly, the travelling motor 26 for the front crawler 12R is forcibly rotated. Thus, during travelling, by observing the speed control encoder 60 for detecting the rotation of the travelling motor 26 for the front crawler 12F, whether the front crawler 12F makes contact with the ground surface or the like can be known. That is, if the detected rotational speed of the speed control encoder 60 sufficiently follows a desired speed instruction to the speed control system, it is found that the front crawler 12F holds a sufficient friction force between itself and the ground surface.
On the contrary, after a front crawler 12F approaches a precipice or a cave-in, when the front crawler 12F suspends while the other three crawlers checks the posture of the robot in disordering so that the weight of the robot cannot be anymore supported sufficiently, this front crawler 12F looses its friction force with respect to the ground surface, and accordingly, no drive force can be obtained from the ground surface. However, since the control loop gain is set to a low value, the detected rotational speed has a positive or negative large deviation from the desired speed instruction value. (At this time, if the motor power is weaker than a mechanical loss, the detected rotational speed becomes lower than the desired speed instruction value. On the contrary, if the motor power is stronger than the mechanical loss, a brake obtained from the ground surface is lost so that the detected rotational speed becomes higher than the desired instruction value.) Thus, by lowering the control loop gain of the speed control system of the travelling motor 26 for the front crawler 12F, a deviation in the speed control system greatly varies in dependence upon a ground contact condition of the front crawler 12F, and accordingly, by monitoring the degree of this deviation, the ground contact condition of the front crawler 12F is detected contrarily, that is, a load exerted to the front crawler 12F is detected, thereby it is possible to determine whether the front crawler 12F comes to a precipice or the like or not.
When the robot comes to a precipice or the like, there is a tendency such that both front crawlers come off from the ground surface in its entirety so that it is inclined downward forward. Such a condition can be found by monitoring the output of the inclinometer 64 for detecting an inclination of the robot body 10. However, the robot does not always incline even though it comes to a precipice or the like. That is, as mentioned above, it is in such case that one (for example, the left side one) of the front crawlers 12F alone comes off from the ground surface while the other three crawlers hold the posture of the robot in disordering. At this time, the fact that the front left crawler comes to the precipice or the like can be detected by monitoring a deviation between the left and right speed control systems for this front left crawler 12F. With this arrangement, since a deviation between the left and right speed control systems of the front crawlers 12F is monitored, in addition to an output Φ from the inclinometer 64, the fact that the robot comes to a precipice or not can be surely found even though the forward inclination of the robot body 10 is not definitely detected.
A predetermined computing process is carried out in accordance with outputs of the inclinometer 64 and deviations in the speed control systems which have been sampled by the control device 50 so as to obtain a threshold value Φ0 of the inclined angle for determining whether the front crawler 12F comes off from the ground surface or not, and a threshold valve T0 of the crawler load T, and these values are stored in a predetermined memory. The above-mentioned threshold values can be obtained by calculating an averaged value in a predetermined period, or a dispersion or a standard deviation in a predetermined period (step 202).

(2) Come-Off Detecting Process

Subsequently, the control device 50 determines whether or not the load T exerted to the front crawler 12F is below the threshold value T0 (step 203), and also determines whether or not the inclined angle Φ from the inclinometer 64 exceeds the threshold value Φ0 (step 204).
As a result, if it is determined that the load T of at least one of the front left and right crawlers 12F is below the threshold value T0, or if it is determined that the inclined angle Φ from the inclinometer 64 exceeds the threshold value Φ0, it is determined that there is a risk of a downfall of the robot so that the procedure is advanced to step 205.
That is, as shown in Fig. 17(b), if the inclined angle Φ exceeds the threshold value even though a load greater than the threshold value T0 is exerted to the front crawler 12F, it is determined that there is a risk of a downfall of the robot. Further, if a load T exerted to either one of the front crawlers 12F is below the threshold valve T0 even though the inclined angle Φ is below the threshold value Φ0, it is determined that there is a risk of a downfall of the robot. In this case, such a condition that one of the front left and right crawlers 12F drops down to an inclined surface of a precipice or the like while the other three crawlers hold the posture of the robot in disordering, is indicated, as mentioned above.
Further, sometimes, the front crawlers 12F all come off so that a value Φ detected by the inclinometer 64 exceeds the threshold value Φ0, and the load T becomes lower than the threshold value T0 (refer to Fig. 17(c)). However, since the robot takes such a survey posture that the front crawlers 12F are extended forward, the bottom of the robot body 10 is caught by a position just before the inclined surface so that the gravitational center G of the robot body is positioned just before the inclined surface, and accordingly, the robot does not soon fall down even if the front crawlers 12F alone drops down onto the inclined surface of the precipice or the like.

(3) Landing Determining Process

At this time, it is not yet understood where a cave-in in front of the robot is shallow so that the robot can land as it advances or a deep precipice is present so that the robot falls down as it advances. Accordingly, in order to avoid a risk of a downfall, an instruction for rotation is delivered to the power source device 56 for driving the travelling motors 26 which are therefore driven under control. As a result, the robot is decelerated. Simultaneously, an instruction for turning is delivered to the power source device 58 for driving the turning motors 36 which are therefore driven under control in order that the front crawlers 12F are made to stand upright so that their forward ends 12a are located at vertically lowermost positions. As a result, the front crawlers 12F are turned by a predetermined angle toward the gravitational center G of the body as indicated by the arrow D in Fig. 17(d), and accordingly, such a posture that the longitudinal direction of the front crawlers 12F are vertical is taken (step 205).
Next, drive control for the travelling motors 26 is carried out in such a way that a process of advancing the robot by a predetermined distance at a slow speed and a process of going back the robot by a predetermined distance at a slow speed are successively carried out. Such an advancing process at a slow speed and a go-back process at a slow speed are repeated successively more than one time (step 206). During carrying out such processes, it is determined whether or not a load T exerted to either one of the front left and right crawlers 12F exceeds the threshold value T0 (step 207). As a result, if it is determined that the load T exerted to the front crawler 12F exceeds the threshold value T0, it is determined that there is a shallow cave-in or precipice at which the front left and right crawlers 12F can make contact with the ground in such a posture that they are made to stand upright, that is, it is determined that the robot can advance and land as shown in Fig. 17(f). Then, the procedure is shifted to step 208.
Meanwhile, if a load T exerted to either one of the front left and right crawlers 12F is below the threshold value T0, it is determined that there is a deep cave-in or a high precipice at which the front crawlers cannot make contact with the ground even through they are made to stand upright, that is, it is determined that the robot should fall down if it would advance as shown in Fig. 17(e). Then procedure is shifted to step 209.

(4) Landing Process

At step 208, an instruction for applying engine brake to the rear crawlers 12R is at first delivered to the power source device 58 for the travelling motors, and accordingly, the travelling motors 26 for the rear crawlers 12R are turned off. Simultaneously, an instruction for advancing the robot at a slow speed by means of the front crawlers 12F is issued. Accordingly, the robot is advanced at a low speed with the rear crawlers 12R being braked. Meanwhile, during this advance, the turning motors 36 is driven under control so that they are gradually turned toward the gravitational center G of the body further from the upright standing posture as shown by the arrow F in Fig. 17(f). Accordingly, the robot descents with a stable posture without the robot body 10 being abnormally inclined, and can safely land (step 208).

(5) Downfall Avoidance Process

Meanwhile, at step 209, the travelling motors 26 are at first driven under control so that the robot comes once to a stop. Next, the travelling motors 26 are driven under control so that the robot goes back. Simultaneously with this go-back, the turning angles of the front crawlers 12F are controlled so that the front ends 12a of the front crawlers 12F which have been extended in front of the robot body 10 are gradually turned toward the gravitational center G of the body by way of a position above the robot body 10, and finally, the turning angles θ of the front crawlers 12F are set to zero. That is, the front crawlers 12F are returned into the reference posture. By carrying out the above-mentioned process, the front crawlers 12F are returned to a condition in which they make contact with the ground surface just before the inclined surface from a condition in which they are projected from the inclined surface, thereby it is possible to prevent the robot from falling down. Further, the travelling motors 26 are driven under control so that the robot 12 comes to a stop when the front crawlers 12F make contact with the ground surface just before the inclined surface.
It is noted that a warning signal may be delivered to the remote-control transmitter 46 by way of the remote control receiver 48 so that a buzzer or a lamp which is incorporated in the transmitter 46 and which is not shown is energized in order to call the attention of the operator when the process is shifted to step 209.
If the robot comes to a stop after the front crawlers 12F make contact with the ground surface just before the inclined surface, the operation mode is turned into a manual control mode carried by the operator. The operator himself examines the height of the precipice and so forth so as to determine whether the robot can descend under manual remote-control or another path should be selected, or whether the advance should be enforced with the use of a winch for climbing a steep slop which is attached to the robot body 10 or not, and then he manipulates the remote-control transmitter 46 so as to safely run the robot in accordance with his determination.
As mentioned above, according to this embodiment, it can be automatically and precisely determined in accordance with an inclined angle of the robot body 10 and a load exerted to the front crawlers 12F that there is a risk of a downfall of the robot, and the travelling and turning of the robot is automatically and surely controlled so as to prevent the robot from falling down. Accordingly, without dependence upon the operator's abilities of monitor and manual operation, the downfall accident of the robot can be automatically and surely avoided, and further, the operator can prevent himself from paying attention to the monitor and operation of the robot, in comparison with the conventional one, thereby it is possible to alleviate the operator's fatigue. Accordingly, it is possible to prevent the operator himself from falling down or the like caused by his fatigue, thereby it is possible to ensure the safety for the operator.
Although determination whether the height of a precipice is low so that the robot can advance further or it is high so that the robot falls down if it advances, is made after the determination that there is a risk of a downfall of the robot is made in this embodiment, such a determination can be eliminated as the case may be. That is, when determination is made such that there is a risk of a downfall, the robot may be directly returned to the condition shown in Fig. 17(f), and thereafter, it can be manually controlled by the operator. Further, the downfall avoidance operation is made such that the front end sections of the front crawlers 12F which are extended forward are turned rearward while the robot is moved back. However, such an operation is only one of examples, any pattern of turning operation can be used if it can surely perform a downfall avoidance operation with the use of the crawler's characteristics such that the crawlers can be turned by any angle within a 360 deg. range.
Further, in this embodiment, although a load exerted to the front crawlers 12F is detected in accordance with a deviation in the speed control system of the travelling motors 26 for the front crawlers 12F, whose control loop gain is lowered, it can be detected in accordance with an armature current if the travelling motors are D.C. motors, or an output signal from an A.C. servo-amplifier if the traveling motors are A. C. servo-motors. Further, a toque exerted to the front crawlers 12F can be detected directly by a torque sensor. Further, a load can be also detected in dependence upon whether or not the motors 26 are rotated when the front crawlers 12F are towed after the travelling motors 26 for the front crawlers 12F are deenergized.
In this case, the value of the load can be detected by the speed control encoder 60.

Claims

A disaster relief robot in which pairs of left and right crawlers (12F, 12R) with rubber tracks (18) are provided to a robot body at front and rear sides thereof, sprockets (20) in said crawlers being driven under control, independent from each other, a track frame (16) for each of said crawlers is pivotably attached to the robot body (10) through the intermediary of a pivot shaft (14), which is arranged transverse to the track frame and parallel to the rubber track surface and being located on one end side of said track frame, characterized in that the distance between the pivot shafts (14) in the front and rear crawlers is set so that maximum turning loci do not interfere with each other, and the robot body (10) has a gravitational center which is set at a position intermediate of the distance between the pivot shafts in the front and rear crawlers.
A disaster relief robot as set forth in claim 1, characterized in that a torque limiter (34) is arranged intermediate of a turning power transmission system of the track frame for said crawler.
A disaster relief robot as set forth in claim 2, characterized in that a sensor (44) for detecting a turning angle is provided in the turning power transmission system between said torque limiter and said track frame.